President Hu Jintao of China will arrive in Cannes this week pondering a plea from Europe for tens of billions of dollars to help the continent get out of its debt crisis. And President Obama will arrive with a smile, some hearty handshakes, and his own plea: that Greece get its act together and that Europe fix its economic ills, which he has called one of the biggest drags on the United States? own ailing economy.

The two contrasting appearances at the G20 economic meeting are a stark example of waning American influence. Without the spare cash that Hu has at his disposal ? and the power that can come with it ? Obama has struggled to cajole his own allies into taking the steps he believes are necessary to lift the global economy.

Yet the relative decline of the US as an international force also comes with a silver lining. For decades, the US has been the global rescuer of last resort. It is a role that has brought significant costs, both financial and human.

The last few months may well end up being an inflection point, in which the US, though easily still the world?s leading power, no longer has quite the responsibility or the burden it once did. The pattern has been evident in the Arab Spring, with the American military playing mostly a supporting role in Libya, and now in the European financial crisis, with Asian money coming to aid the Europeans.

?Why would the US want to have influence over a train wreck?? said George Friedman, the chief executive of Stratfor, a geopolitical risk analysis company. ?If the Chinese want to provide $150-billion bailing out European banks, more power to them.?

In many ways, the situation is a natural evolution of the campaign promises made by Obama in 2008, when he vowed to turn away from the Bush administration?s more unilateral approach.

As president, Obama is now overseeing the withdrawal of all troops from Iraq and has emphasised multilateral diplomacy in all its messy forms. He refused to consider American intervention in Libya until the United Nations approved a resolution supporting it, and then he stepped back and allowed France and Britain to take the lead though American military help remained essential.

Obama?s critics have decried the decline in American clout and said his approach exacerbated it, by forfeiting claims on American exceptionalism. Obama?s backers say that he is simply acknowledging reality and developing a clear-eyed strategy for what the US can and cannot do and that he ultimately may prove right in diagnosing Europe?s economic problems and its need to take difficult steps to fix them.

?Obama has clearly made a premeditated move away from the unilateralism of the Bush years, and he?s done it because it?s the right way to conduct foreign policy, but has also done it because America?s leverage has been diminished,? said David . Rothkopf, a commerce department official in the Clinton administration and the author of ?Running the World,? a book about the National Security Council. ?We can?t write checks the way that we once could; we can?t deploy troops in the way that we once did.?

But, Rothkopf argues, ?we are in this situation of feeling overexposed and overburdened precisely because we had such an appetite before for unilateralism and triumphalism.?

Of course, in an election year, the last thing that Obama wants to be seen as doing is putting forward the idea that the US is no longer influential, or that there is no longer any such thing as American exceptionalism. In Cannes, Obama will be trying to balance providing that leadership while not taking on any of the additional burden ? particularly financial ? that such leadership often requires.